Bio-reduction of sulfide minerals to recover invisible gold

摘要: Sulfide minerals, like pyrite and arsenopyrite, are of economical interest due to the presence invisible gold locked inside these minerals. As fine grinding is often not sufficient liberate from additional destruction techniques, based on chemical biological oxidation processes, required access via cyanidation. These techniques have proven be successful reach satisfactory recoveries, but operation costs high challenging waste streams (sulfuric acid) produced. an alternative methods in this thesis bio-reduction sulfide minerals was proposed investigated. Bio-reduction, use hydrogen convert mineral-sulfur sulfide, has as major advantage that can recovered solution (to produce bio-sulfur) leaving a stream without diluted sulfuric acid. Furthermore, electrical energy will saved. Theoretically, more environmental friendly should work, no reaction observed practice. It appeared sulfur/sulfate reducing bacteria were able sulfur when fixed crystal lattice arsenopyriteat selected conditions (pH 5, 35oC). In order make bio-available for first enter solution. combination between partial bio-oxidation therefore Partial at pH 2 results formation elemental sulfur, which serve substrate 5 bacteria. This combined method found 35°C, leachability used concentrate increased 6% 39%. Optimization process needed recoveries >90% 1 or ox/red cycles, new (called Paroxsul process) with lower impact, less costs, application large number ready introduced precious metal industry.